The value of taller bikes is somewhat lower than nominal size like a 56 or 58 but in general since there are less of them it is not much lower.

I think the frame is around a '84/85 Sport or maybe a Brava. Your bikes are different from ours so it is hard to tell for sure, I believe some Bianchis did come with chrome forks up there but not many lowerend did here usually just "socks"

A really large frame, such as the one depicted, is very hard to find a buyer for. And when you do find a buyer, there will likely be only one. The size of the bicycle, to me, renders it to be a very poor buy, if flipping in intended.

As for the all chrome fork, no problem. I have owned several similar Bianchi bicycles, and some were fitted with an all chrome set...

+1 To Randy's comment. I have greatly discounted XL frame bikes, and even then, it has taken as much as a year to find a buyer. I have three XL bikes right now....
On vintage racing bikes, small frame sizes sell for a premium, the smaller the frame, the larger the premium. "Regular" sizes sell fine. XL are hard to sell and sell at a sizable discount.

These comments are on mid range or lower bikes, which a 105 Bianchi would be IMHO.

I had a XL Bridgestone. The only Bridgestone roadie I've ever had. We all know how easy it is to sell a Bridgestone, even an entry level bike. Well, this 25" framed bike finally flipped for me on CL at $60. I had only two hits on the ad. If that were a standard sized Bridgestone, it probably would have gone for more than double what I finall got.